The present invention relates to a security system for monitoring a prescribed area by using a device for transmitting light or electric wave and an imaging device.
As prior art, there is an indoor security system which detects a person and the like in a building by using an FM-CW type radar and captures the image with a camera (see Japanese Patent Application Laid-Open No.2000-3478).
An FM-CW type radar antenna's beam width (electric wave transmission angle) must be narrow in terms of principle, which results in one antenna detecting only a narrow area (normally, 10 degrees or less). Therefore, to ensure the entire area to be monitored, it is necessary to adopt a method that scans the monitoring area by making an antenna rotate back and forth or a method that sequentially switches a plurality of antennas arranged in line. Thus, the above-mentioned prior art has a problem in that the entire monitoring area cannot be simultaneously monitored, which decreases accuracy of intruder detection. Furthermore, if the above-mentioned prior art is applied to an outdoor security system which monitors an area around a building, it is necessary to arrange a large number of antennas around the building, thereby making wiring and installation work cumbersome and complicated and increasing installation and maintenance costs.
Moreover, the above-mentioned prior art detects the existence of a mobile object and the number of objects according to changes of the spectrum of the beat signal in the monitoring area and also makes it necessary to record information by the hour. If it is applied to an outdoor security system, there are the problems of increased storage capacity and costs because increasing arithmetic processing requires a high-performance processing unit.